#include<iostream.h>
#include<iomanip.h>
#include<math.h>
const double pi=3.1415926;

double area(double a,double b,double c)
{
	double l=(a+b+c)/2;
	return sqrt((l-a)*(l-b)*(l-c)*l);
}

int main()
{
	double a,b,c,l;
	int number=1;
	while(cin>>a>>b>>c>>l)
	{
		if(a==0&&b==0&&c==0&&l==0) break;
		double s=area(a,b,c);
		double L=a+b+c;
		double R=2*s/L;
		double r=R*(L-l)/(L-2*pi*R);
		if(l<=2*pi*R)
		cout<<"Case "<<number++<<": "<<setiosflags(ios::fixed)<<setprecision(2)<<(l*l)/(4*pi)<<endl;
	    else
		cout<<"Case "<<number++<<": "<<setiosflags(ios::fixed)<<setprecision(2)<<s*(R-r)*(R-r)/(R*R)+r*L*(R-r)/R+pi*r*r<<endl;
	}
	return 1;
}
